The present invention relates to a heat exchanger assembly, for example, a radiator employed in automotive applications, and a method of manufacturing such assembly.
In recent years, heat exchangers such as engine cooling radiators for high production automobiles and light and heavy trucks have been made with thermoplastic inlet and outlet tanks. Examples of such types of heat exchangers are found in the following U.S. Pat. Nos. 4,461,348, 4,531,578, 4,600,051, 4,651,815, and 4,544,029, as well as U.K. Patent Application No. 2,108,648. The tanks generally have an open side with a flanged edge, and are assembled to the heat exchanger headers by crimping a channel around the header plate over the flanged tank edges. The joint is sealed by means of an elastomeric gasket arranged between a tank and a header. This type of configuration generally provide a less expensive assembly than soldering, bolting or otherwise bonding or mechanically securing the tanks to the headers. The use of plastic tank material is less expensive than the usual drawn brass, steel or stainless steel tank. Additionally, the assembly operation is faster and requires less skill.
While these types of conventional heat exchanger configurations utilizing plastic tanks are useful in many applications, they have drawbacks when contemplated for use in low volume motor vehicle and other applications because of the fact that expensive and inflexible tooling is required for molding the plastic tanks. Examples of such low volume applications are street sweepers, airport service vehicles and the like, and some heavy duty truck applications. Other low volume applications include stationary applications such as engine driven generator sets. Plastic tanks cannot be reconfigured easily, for example, to move the location of inlet or outlet ports or to add brackets or fittings. In addition, without elaborate reinforcement, the plastic material of the tank is generally not strong enough to allow the heat exchanger to be mounted by means of the tanks. Furthermore, in some heavy duty applications, the plastic tank material has been found to lack strength in the area where the inlet and outlet ports join the tanks, resulting in field failure due to shock and vibration. Metal tanks would provide better strength in this regard if they could be configured for maximum flexibility in manufacturing.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a heat exchanger assembly which provides increased strength and durability in heavy or severe duty applications.
It is another object of the present invention to provide a heat exchanger assembly which, for low volume applications, permits inexpensive changes in configuration of access openings, such as inlet and outlet ports, without expensive tooling changes.
It is a further object of the present invention to provide a heat exchanger configuration which permits the use of metal castings for the tank components.
It is yet another object of the present invention to provide a heat exchanger assembly which utilizes a cast metal tank but which is not susceptible to internal corrosion problems caused by coolant stagnation in crevices therein.
It is a further object of the present invention to provide a method of making the heat exchanger which meets the aforestated objects.